The invention relates to a locking device for a pneumatic phase module having for each phase of operation of an automatic sequencing device a bi-stable memory, which is contained in a removable housing having a bearing face provided with first communication orifices and adapted to be applied on a fixing surface of a base having second communication orifices cooperating with the first communication orifices, the memory further having a control input for placing it in logic state "1", a cancelling input for placing it in logic state "0" and an output, the base comprising further, for feeding the orifices,
(i) channels capable of cooperating likewise with corresponding channels of identical adjacent bases for conveying the feed pressure,
(ii) channels for transmitting control signals to a following base,
(iii) channels for sending a cancelling signal to a preceding base, and
(iv) channels transmitting general re-set to zero signals, and an AND gate, with two inputs and one output, associated with each memory in such a manner that one of its inputs receives cancelling signals arising from the performance of an operation, and that its other input receives the output signals coming from the memory, the output of the AND gate transmitting a control signal to the control input of the memory of the following phase module of the automatic sequencing device.